President Trump pronounced the NATO summit a success and himself a "stable genius" in a freewheeling parting press conference that followed a sometimes tense meeting of the western alliance.

Trump spoke to international reporters in Brussels around noon local time Thursday, touting concessions from fellow NATO allies to boost defense spending and downplaying what were at times uncomfortable negotiations.

One reporter asked if Trump's message would change once he departed on Air Force One, perhaps referring to tweets that followed G7 talks, in which Trump turned on Canadian Prime Minister Justin Trudeau and French President Emmanuel Macron.

While inBrussels, Trump pressed members of the 69-year-old alliance to meet their commitment of spending 2 percent of their gross domestic products on defense by 2024.

He said Thursday that the pressure he put on the nations has resulted in a possible increase of $40 billion in defense spending.